Rheostat



4Maurch l2, 1929. R. H. MAxsoN 1,705,299

RHEosTAT' Filed May 5, 1923 Civ Fotontecl Mar. 12, it.

UNITED STA'l-ES 1,705,299 PATENT OFFICE.

'ROLLAND H. MAXSON, OF MILTON, WISCONSIN, ASSIGNOR, BY MESNE ASSIGNMENTS, TO THE BURDCK CUEPGATON, F MILTON, WISCONSN, A CORPORATION OF DELAVARE,

Application filed 5,

This invention relates to rheostats.

It will be explained as embodied in a rheostat particularly adapted for the control olt elf ro-therapeutic appliances.

One ot the objects olf' invention is to provide an improved rl'ieostat.

Another object 'is lo provide a rheostat which may be re 3 ly manipulated.

Another object is lo provide a rheostat which niay be suspended by or, in ell'ect, l'orin a part ot the current supply cord.

Another object is to provide a rheostat, whose install tion in a current supply cord neces italics te cutting o t only one oli Ythe conductor j iairs.

Another object is to pi'ovide a rheostat with which arious appli may he readily connected and disconnected.

rinother object to provitV a rheostat which is reliable, compact, ellicient and n lay be relativery inexpensively and 'eadily nianufaclured.

Other objects and advantages will hereinafter appear.

lilinbodinients oi the invention are illustrated in the accompanying drawing, wherein Fig. 1 shows a current conducting cord and one 'torni ot rheostat.

Fig. 2 is an enlarged longitudinal section oit the rheostat shown in Fig. 1.

Fig. 3 'is a section on the line 8-3 of Fig. 2, and

Fig. l is a longitudinal section of a inodilied forni oi' rheostat.

As shown in F ig. 1, the rheostat 5 inay be located in an ordinary multi-conductor current supply service cord between the source ot current and thel appliance utilizing the current. rlhe rheostat is employed to vary the current tlowine` to the appliance. For convenience ot explanation the service cord may be considered :is eonijfiosed of two sections, a supply section 6 tor connection to the service mains, and a delivery section T Vfor connection (o the appliance. The cord sections may be equipped with suitable plug or other desired type of connectors for attachment to the service niains and the appliances. Ordinarily, of course, the two sections ot' the service cord niay be interchangeably connected to the service inains and the appliances so that the designations which hereafter may be used concerning there nre. he fionsiiilered as appl-,ind to ln Le,

RHEOSTAT.

1923. Serial No. 636,837.

interchangeable and operatively synonoinous elements.

The rheostat illustrated in Figs. 2 and 3 ias a resistor 8, which may consist of a coil i suitahle resistance wire wound on a tubusupport 9. Support 9 may be formed iroin suit; ble insulating material, such as liber. Re stor 8 is enclosed by a tubular metal shell or housing 10 which inay be rovided with ventilating openings 11 il desired.

y One end oi housing 10 is provided with a head which niay be secured in place by screws 1B. Head 12 has an annular groove 1l in inner Ytace for receiving one end ot support 9. A hole passes substantially a iaily through head 12 to altord a passage `ter a section ol the service cord.

n contact head 16 of suitable insulating material, such as liber, is secured in housing 10 near the opposite end thereof. Screws 17 will serve to hold this contact head in place. An annular groove in the inner face ot head 16 receives the end of support 9 so that the resistor is carried by and between heads 12 and 16.

Contact head 16 carries a circularly arranged series of fixed contacts 18 which may be in the form ot flat headed bolts passing through head 16. Fixed contacts 1S are connected to dilferent points on the coil of resistor 8 by taps 19. Suitable nuts 20, threading' Aupon the projecting shanks of contacts 18, serve to anchor the contacts in place in the contact head and niay be utilized to clamp the ends of the respective taps 19 thereto. Contact head 16 has an axial hole therethrough and into this hole a metal lnishing 21 lits. Bushing 21 may be provided with fins or projections 22 to prevent the saine from turning.

rllhe adjacent end of housing 10 is pro vided with an insulating head 25 which may he secured in place by screws E26 and has an axial hole therethrough. A hollow handle extends through hole 27 and the bore ol' bushing 21. This handle comprises a metal tube 28 and linurled knob 29. Knob 29 inay be inode ol. suitable insulating Inaterial secured to tube 28 by a screw 30.

A collar 31 is secured to tube 28 by a lar , the form et a vopper il is adsptntra finition tact 33 re-ty be 'brush wl. nu

ally engage the fiat heads of .tired contacts 18. The tiuning of knob 29 will rotate brush 83 over the llxed contacts. A metal washer 34 may be .interposed between head 25 and collar 3l. A stop 35, in the 'torni of a screw secured in head 1G, will serve to liinit the rotation oll the handle and Contact brush One end ot resistor 8 is connected to a terminal 3G which may take the form of a bolt secured to support 9. Bushing 2l is provided with a suita le terminal such as a screw 37.

, rlhis rheostat may he installed by cutting only one conductor of the service cord and anchoring one oit the severed ends to terminal and the other severed end to terminal 87. 'The uncut. conductor passes directly thiough the rlieostat. Resistor 8 is thus interposed in the circuit, between the power source and the power consuming appliance, and the amount olf resistance may be varied by rotating knob 29.

Fig. 4 shows a, longitudinal Cection of a modified type or rheostat, In this rheostat the resistor is in the form oi a rod of a suitable resistance material, such as carbon. The terminal arrangement for the connection elL the service cord sections also modiied.` This rheostat has a tubular housing 4G and closing heads 47 and 48 somewhat similar to those previously described. Heads 47 and 48 are provided 'with sockets for receiving the ends of resistance rod 45 to support the same.

Head 47 has an axial hole therethrough for accommodating an operating handle. This handle comprises an exteriorly threaded metal tube 50 and a lnurled operating knob 5l secured thereto. Head 50 carries two pin receptacle connector terminals 52 and 53 of any approved design.

A. disc shaped support 54, of suitable insulating 'materiah is secured in housingl 46. This support Vcarries a metal nipple 'which journals one end of tube 50. A screw 56 serves as a terminal lor one of the supply conductors. The other supply conductor may be connected to receptacle termina-l 52. Receptacle terminal 53 is connected to resistance rod 45 by a lead 57.

Tuhe 50 has a threaded nut 5S mounted thereon. 1\lut 58 carries a Contact spring or hrush .vhich engages the surface of resist-ance rod lVhen lnoh 5l is turned it rotates tube 5() and vout 5S moves toward one or the other end ol' the housing. The movement ot nut 58 carries spring or brush 59 along rod 45 and varies the resistance in the circuit.

The delivery section of the service cord may be provided with a suitable pin connector 6() which lits receptacles 52 and 53 to extend the service cord. With this type ot rheostat both conductors oit the suppl cord are cut when installing' the saine. Bota sections of the service cord terminateand are interconnected at the rhe-ostat.

The rheostats herein shown torni compact and reliable variable resistances :tor controlling the current to an appliance. @ne cord section leads into the rhoostat tlirough the axially positioned resistance controlling handle and the other cord section extends the circuit beyond the rheostat. The rheostat is7 in ell'cct7 mounted in the service cord and may be suspended thereby near the oocrator or may be moved about so to be casi'y accessible to the operator. t may be readily connecte-d to and disconnectedfrom the supply mains and various appliances.

Having described my invention What I claim as new and desire to secure by Letters Patent, is

A rheostat comprising an insulating tubular member, resistance element Wound thereon. an insulating head secured to one end et said men'iber, a plurality of contacts said head, connectors from said contacts to points spaced at intervals on said element. sleeve manually rotatable relative to said i bei7 a Contact maker electrically and mechanically connected to said sleeve and rotatable thereby, an insulated conductor eX- tendine' through said sleeve and said mem-r her, and a pair or" conductors adapted to be in electrical circuit with said lirst named conductor, one of said last named conductors being secured to one end of said resistance element and the other being' electrically connected to said Contact maker.

2. A rheostat comprising an elongated tubular casing, a resistance extending longitudinally Within the casing, a. sleeve manually rotatable relative to said casing and said resistance upon the axis oi said casingj an electrical contact brush electrically and mechanically connected to said sleeve and arranged to move when said sleeve rotatedY to electrically connect said brush gressively with successive longitiu portions olf said resistance, an axially bored knob iixedto said sleeveexteriorly ot the casing for turning the sleeve and for ad` mitting conductor cords to the interior ot the casing and electrical connecting terminals associated with said resistance and Ywith said sleeve.

In testimony WhereolE l hereunto subscribe my name.

ROLLAND H. MAXSON. 

